The broad objective of the proposed research is to further basic knowledge about psychological and physiological processes involved in the regulation or voluntary control of human physiological functions by means of biofeedback techniques. More specifically, the current objective is to evaluate the potential of biofeedback techniques in the control and modification of physiological and subjective reactions to stressful stimuli. Studies are proposed on the effects of biofeedback and voluntary control procedures on heart rate changes and subjective reactions to the cold pressor test (immersion of the hand in ice water). Associated physiological, cognitive, and individual differences will be examined. Instructional and feedback influences will be compared in further studies. Comparison will also be made of the effects of feedback for different physiological functions (muscle activity, pulse transit time) and of the effects of other behavioral methods (paced respiration, relaxation, cognitive self-statements). The project will also develop methods for the study of discrimination or perception of changes in one's own blood pressure. Normal volunteer subjects are studied in controlled laboratory experiments of one or more sessions. The experiments are run under the control of a digital computer (PDP-11/GT-40 System) which controls experimental events, creates biofeedback displays, stores and analyzes data. Physiological measures include blood pressure, heart rate, skin conductance, respiration, electromyographic activity from selected muscle sites, pulse transit time, finger pulse and blood volume, and skin temperature. Questionnaires and rating scales are used to assess perceptions of and cognitive reactions to the stressor, individual differences in autonomic awareness, and other variables. This research has implications for mechanisms involved in voluntary control of physiological responses and how it varies under stress and non-stress conditions, for the psychophysiology of "emotion," and for the management of anxiety and pain.